TITLE:   GCN CIRCULAR
NUMBER:  26772
SUBJECT: GRB 200115A: Nanshan-0.6m optical upper limit
DATE:    20/01/15 12:56:33 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Z.P. Zhu, D. Xu, X. Liu, B.Y. Yu, Y. Ma (NAOC), X. Gao (Urumqi No.1 
Senior High School) report:

We observed the field of GRB 200115A (Cenko et al., GCN 26771) using the 
0.6m NEXT telescope located at Nanshan, Xinjiang, China. Observations 
started at 12:11:17 UT on 2020-01-15 (i.e., 20.9 min after the BAT 
trigger), and a series of 300 s R-band frames have been obtained. 
Observations are ongoing.

No optical transient is detected in the Swift BAT's error circle from 
initial frames, down to a limiting magnitude of m(R) ~ 20.0, calibrated 
with the nearby SDSS field.